Metric System

An Overview of the Concepts

of Mass, Volume, Length,

Temperature, and Density

Length

Definition

– The distance between two points along a

straight line

Units of Measure

– Meters (m) – base unit

Measuring track distances (100m dash)

– Kilometers (km) – large distances

Measuring distances between cities

Length (cont.)

Units of Measure

– Centimeters (cm) – small lengths Measuring dimensions of a textbook

– Millimeters (mm) – small lengths Measuring the width of your pupil

– Smaller units Micrometers (m) or nanometers (nm) – measuring the size of cells

Tools for Measurement

– Metric ruler or meter stick

Volume of Liquids

Definition

– The amount of space an object occupies

Units of Measure

– Liters (L) – base unit Measuring soda bottles (2L bottles)

– Milliliters (mL) – small volumes Measuring liquid in eye droppers

Tools for Measurement

– Graduated cylinder – measure at the bottom of the curve, called the meniscus

Volume of Solids

Definition

– The amount of space an object occupies

Units of Measure

– Cubic centimeters (cm3)

– 1 cm x 1 cm x 1 cm

– 1 cm3 is equal to 1 milliliter (mL)

– 1 m3 is equal to 1000 liters (L)

1 cm 1 cm

1 cm

Volume of Solids (cont.)

Tools for Measurement

– For rectangular solids, use a ruler

Volume = Length x Width x Height

– For irregular solids, use a graduated cylinder

to see how much volume of water is displaced

Fill a graduated cylinder half full and measure the

original volume

Place the solid (rock, marble, etc.) in the cylinder

and measure the new volume

Subtract the original volume from the new volume

to get the volume of the solid in cm3 or mL

Mass

Definition

– The amount of matter inside an object

– The mass of an object does NOT change

based on location

– Weight, on the other hand, does change

based on location (due to gravitational forces)

Mass (cont.)

Units of Measure

– Gram (g) – base unit Measuring mass of coins or small rocks

– Milligram (mg) – smaller masses Measuring amounts of medicine (500 mg)

– Kilogram (kg) – larger masses Measuring large fossils

– Metric ton (t) – really large masses Equal to 1000 kg or 1 Megagram (Mg)

Measuring mass of a dinosaur

Mass (cont.)

Tools for Measurement

– Triple beam balance

The instrument has 3 beams that are used to

measure objects

– 10g beam

– 500g beam

– 100g beam

Mass (cont.)

Tools for Measurement

– Triple beam balance

Steps to Operate the Balance

– Set all the beams to zero

– Place an object on the pan

– Start with the heaviest beam (500g), then move to the

next heaviest beam (100g), and finally to the lightest

beam (10g)

– Slide riders across each beam until the beam tips

– Use the lightest beam to balance the pointer at zero

– The mass of the object is the sum of the readings from

each beam

Density

Definition

– The relationship between an object’s mass

and it’s volume

– The mass per unit volume of a substance

– Density = Mass/Volume

Units of Measure

– Grams per milliliter (g/mL) – base unit

– The density of water is 1 g/mL

– 1 gram of water occupies 1 milliliter of volume

Density (cont.)

If an object is more dense than water, it

will sink

– A rock, an anchor

If an object is less dense than water, it will

float

– A piece of wood, a plastic bottle

Temperature

Definition

– A measurement of how hot or cold something

is

Units of Measure

– Degrees Celsius (°C) – the unit we will use

Scale was set so 0°C equaled the freezing point of

water and 100°C equaled the boiling point of water

100 equal divisions between 0°C and 100°C

Temperature (cont.)

Units of Measure

– Kelvin (K)

Kelvin, a British physicist, wanted a temperature

scale with an absolute zero, below which

temperatures did not exist

Absolute zero is estimated to be 0 K

To convert from Celsius to Kelvin, add 273 to

Celsius temperature

Tools for Measurement

– Celsius thermometer